A Caution on GPS Truck Data Presented at 15 th Applications Conference Atlantic CityMay 2015 William G. Allen, Jr., PE Consultant, Windsor, SC

2 Observed Truck Data Very difficult to obtain Surveys are expensive, unreliable GPS data is available via ATRI – American Transportation Research Institute – part of American Trucking Association – a cost-effective option – probably available nationwide – Jeff Short, (703)

What Is It? Large trucking fleets carry GPS units Latitude/longitude and time stamp ATRI geocodes to your TAZ system Tens of millions of records Available for most urban areas Every day for a couple of months 3

My Experience Four-step truck model – Kansas City Tour-based truck models – Atlanta – Birmingham 4

The Good News Good data on location, time, speed – valuable for trip distribution, time of day Data for multiple days is helpful Less expensive than surveys 5

The Bad News Challenge of big data No data on truck type or operator – confidentiality is a problem Only certain trucking companies included – mostly long-haul – no owner-operators – skewed sample Difficult to expand to the universe 6

More Bad News GPS pings are random Many data anomalies – movement but no elapsed time – elapsed time but no movement Multi-day files may include same truck Geocoding is problematic – internal OK – external is difficult 7

Processing Big Data Size of database dictates processing methods Must process carefully to identify trips or tours – various algorithms exist – no standardization – software differences 8

What is a “Stop”? If speed < 3 mph, truck is probably stopped Maybe truck moved a little but didn’t leave the zone – drayage or bad data? How long can a stop last? Is origin of trip X always the same as destination of trip X-1? 9

10 So What? Truck GPS data can be useful and cost- effective Can’t build an entire model with it Difficult to process – a variety of skills needed Not a perfect solution -- tread carefully

11 Questions? (803)